Our hypothesis is that subcutaneous administration of BNP in human with mild CHF will result in a rapid increase in plasma BNP and cGMP leading to increases in urine output and sodium excretion, secondary to associated increases in glomerular filtration rate and renal blood flow in association with a decrease in distal tubular sodium reabsorption. These actions will also occur in association with increases in cardiac output and decrease in SVR in the absence of activation of the RAAS. The specific aims of the study are to compare cardiovascular, renal and endocrine functions in mild human CHF receiving low dose (5 ug/Kg) with high dose (20 ug/Kg) of subcutaneous BNP; and to define cardiovascular, renal and endocrine functions in humans with mild CHF after receiving five doses of subcutaneous BNP every 12 hours over a 72-hour period.